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I had an electric fuel pump installed as per BIGKEV. Now, the car starts much faster taking a load off my expensive starter and solonoid with the freshly machined copper guts!

late to this party, but I'll toss in some opinions to snack on.

1st, show of hands and be honest, when is the last time anyone has experienced real vapor lock? Me personally, in the mid 90s. Actual vapor lock. Today's fuels fairly well stave off the old menace. Given the heat and operating conditions of new cars it makes sense. The only way you MIGHT see it is if there's a heater hose or exhaust really close to the fuel supply line.

2nd, again with today's fuels being the topic, evaporation is pretty dadgum quick. Park your car in July, forget it for 2-3 weeks. Go out and crank away even after the long pedal was tapped a few times. Nuthin, right? because it mostly evaporated out of the carb on that hot engine and continued as it sat in the hot garage for weeks at a time. It happens so we have to deal with it. I too don't like the idea of cranking away on old 6V starters. High amp draw, heat, junk batteries mostly, why allow that which gives us pleasure create a hemhorroid in our fun?

All you need is a simple pump you can draw thru, as stated above, prime the system and go. Not once have I ever had a failure or loss of reliability having an electric pump in the system. True, "they" didn't have one when new, and they had good ol gas with more "heavy end" molecules than we have today and it was a bit more stable. Also, in their heydays the cars didn't sit for weeks on end. They were used year 'round and never had to worry generally speaking. I don't recommend high output with return lines, regulators, calculated flow, blah-biddy-blah-blah-blah. That OEM pump can exceed the performance needs as it is, your little ticker pump won't work it that hard. Sorry to be a dick about it if it came off that way. Just keep it simple and you're good to go. For the science hobbyist, a gasoline engine needs 0.5 lbs of fuel per HP hour. Fuel weighs 8 lbs/gal. Work back from there, and each fitting can restrict flow by 1-5% depending on use and location. I used to know the volume loss per foot on fuel line but that was my drag race days which are sadly long gone. Enjoy...

i just finished my 1940 160 with the 356, i had put a low presure elec pump in but it fuel starves when it's off and floods when it's on continuously. what 12v elec pump do you reccomend?

Assuming you are using the solenoid type electric pump that mechanical pumps can pull thru when the electric is off, It seems the 6v aftermarket pumps are only available with 5/16 ports. One issue another poster ran into with a different engine is in a pump with 5/16 ports, the fuel passages inside the electric pump are actually smaller than the advertised size. That could be causing the starving issue when the pump is off but with flooding when the pump is on, I would wonder what the actual output pressure might be. Perhaps the pump is faulty or labeled wrong. Not sure if a 12v pump would be the best if the rest of the car is still 6v but Airtex does make a relatively low pressure model (5-9 psi) with 3/8 ports. That high end number is pushing it for a carb even if the pump is located by the fuel tank and pushing thru filters etc so there might still need to be a pressure regulator in the line.

On the starving issue, he tried a different brand 5/16 pump with similar results. I think his fix was to rig a pair of tees to bypass around the pump similar to what is needed with a rotary pump only using a larger diameter check valve. Don't remember if he used 3/8 or 1/2 for the bypass and check valve but by using that and what fuel still flows thru the electric pump when it is off the mechanical pump could pull thru at about the same capacity as the normal intact 5/16 fuel line. If you try something like that be sure to get a check valve with the lowest minimal opening pressure you can find. Most are around 1 psi but some specialty valves can be found that are rated at about half that.

Just now seeing a few 6 volt low pressure fuel pumps for sale for around 35.00 on Amazon with prime one day shipping. Being here in Vegas finally installed one on my 1940 180 about a year ago and works great. Mounted it behind the rear driver side tire. The fuel line arches up over the axle at that point and there was conveniently a hole in the body right there. I take off the metal filter and use a clear plastic, available from any parts house, filter to be able to see if any crud is coming from the gas tank, and better to know when to change. The clear plastic filter come in three inlet and out let sizes so you need to match the pump and line sizes.
You don't want a rotary type as it can stop at a point where it will not allow the mechanical pump to pull through it.

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Are you running a fuel pressure regulator in-line with the fuel pump? My '29 is running strictly on an electric pump, and I sometimes have an issue with flooding on starting it if it has been sitting longer than I should have let it, but generally speaking, it runs quite well with the direct feed from the pump. I've got the psi dialed back to 2 psi and that big rascal seems quite happy with that, it was running too rich at 3-1/2 psi.

no regulator. i bypassed the electric pump which is an edelbrock vane type. and the mechanical pump test out fine, i wonder if the two together put out too much pressure but the mechanical can't pull through the elec one

Typically the vane type pumps must always run as a standard pump can't pump through them. In the rare occasion that I've had a Packard with an electric pump (which is only if I bought it that way) it is always the diaphragm type which has check valves just like the mechanical pump so will have flow whether powered or not.

To farther expand on Don's comment this is the typical way an electric rotary or vane type pump needs to be plumbed in order for the mechanical pump to be able to pull any fuel thru when the electric is off.

When electric is off the mechanical is pulling thru the check valve and when on, the check valve prevents flow from going backward to the tank or just circulating thru the pump again. This same plumbing could be used if internal passages in a solenoid or diaphragm type pump is found to be restricting too much of the flow.

In cases where the electric is putting out too much pressure an optional regulator could be installed after the electric pump but before the second tee. That location would regulate the pump output but not affect the mechanical pump being able to pull thru the check valve.

A larger check valve could be used although finding the combo fittings for the different sizes used might be harder than straight size fittings.

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I agree with Don, get rid of the vane-style pump and go with a diaphragm type pump, and do install a fuel regulator.

I ordinarily am not a big advocate of electric pumps on the older cars but again, as Don said, mine already had an electric pump on it (one that was way too big) and the gravity feed pump is gutted and is just along for the ride and its good looks. They even plumbed it with lines that go back under the car and stop!

That said, it's hot down here in Louisiana, and the electric pumps do at least prevent vapor locking issues, but, you've gotta' keep the psi down or flooding will occur.